"When flawed air and vapor barriers caused this roof to decay, a new venting system was the answer"

The debate between proponents of unventilated
"hot" roofs and ventilated "cold" roofs has been raging
for years. Hot roof advocates argue for sealing all
wall penetrations against convection (at outlets and
vents stacks, for instance) and applying a perfect vapor
barrier. They claim that these measures keep moisture
from entering rafter bays, thus eliminating the need for
a ventilating air space between the roof insulation and
the sheathing.
Cold roof advocates like me admit that it is theoretically
possible to build an unventilated roof, but caution
that it is almost impossible in practice to build it to perfection.
The most conscientious builder will still have
trouble installing insulation, caulking, and vapor barriers
to the